Dose indicators

ABSTRACT

The present disclosure relates to a dose indicator for a pressure-actuated metered dose inhaler (pMDI) device. In an embodiment, the dose indicator comprises a chassis element having a viewing portion, a display element located within the chassis element, a resilient deformable element, and an indexing element having an axis, translation of the indexing element along its axis from a first position to a second position causing deformation of the resilient deformable element in the same direction as translation of the indexing element resulting in generally greater displacement of portions of the resilient deformable element nearer to the axis relative to portions thereof further from the axis, the displacement of the portions of the resilient deformable element in the same direction as translation of the indexing element inducing indexing of the display element from a current position to a subsequent position relative to the viewing portion of the chassis element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of United Kingdom Patent ApplicationNo. 1215917.4, filed Sep. 6, 2012, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to improvements in or relating to doseindicators, and is more particularly, although not exclusively,concerned with dose indicators for pressure-actuated metered doseinhaler (pMDI) devices.

BACKGROUND TO THE INVENTION

Patients that need to use inhalers, such as pMDI devices, regularly havelong had the need to be able to monitor their inhaler usage, andregulators of medicines have started to specify that some indication ofwhen an inhaler is reaching the end of its recommended number ofactuations as well as when it has reached or exceeded that number isintegrated into the inhaler product. Dose counters (providing anaccurate count of the number of doses remaining) and dose indicators(providing an indication of the number of doses remaining) have beenproposed for use with inhalers. Yet, to date not many of the proposeddose counters or indicators for pMDIs have reached the market in a pMDIproduct. In most dose counters and dose indicators, the display istypically advanced each time the inhaler device is used, and it isparticularly important that they do not undercount the number ofdispensed doses as, in extreme cases, the patient may rely on the countshown on the pMDI device to receive life-saving medication. In dosecounters or dose indicators, it may be acceptable for advancement of thedisplay to be triggered (initiated) before or after the dose has beendelivered, so long as it is practically impossible for the patient totrigger it without dispensing a dose. However, some of these dosecounters or dose indicators are designed to require electronics whichincreases the cost, prevents the user from washing the device, may havebattery life issues and, in the case of dose counters, may havedifficulty obtaining regulatory approval for their use. In addition,many of these dose counters and/or dose indicators are complex requiringlarge numbers of small mechanical parts which gives rise to high costs,difficulties in assembly, and the requirement for complex dimensionaltolerances. The added cost has long been a disincentive to productdevelopers to incorporate a dose counter into an inhaler. In someinstances, the dose counters and dose indicators require a re-design ofwhat has become a standard shape and size of pMDI to significantlylarger, bulkier and more awkward shapes. In addition, the character sizeand legibility of the display of such devices can be poor, making itdifficult for a user to read them.

Examples of pMDI inhalers or devices having either dose counters or doseindicators are described in GB-A-1317315, WO-A-93/24167, U.S. Pat. No.7,806,295, U.S. Pat. No. 5,421,482, U.S. Pat. No. 6,679,251,WO-A-02/91293, GB-A-2385640, WO-A-2006/119766, WO-A-2006/126965 andWO-A2008/025087.

GB-A-1317315 discloses a dose indicator that can be mounted in a pMDIactuator and which comprises four sets of advancement teeth which aresprung-loaded together. GB-A-2385640 discloses a dose indicator which ismountable within a pMDI actuator and which uses sets of fine teeth toadvance the indicator.

WO-A-93/24167 discloses a two-component dose indicator that is mountedat the top of a pMDI actuator. WO-A-2006/126965 discloses a top-mounteddose indicator. WO-A-2008/025087 also discloses a top-mounted pMDI doseindicator in which an indicator ring component bears integral springarms.

U.S. Pat. No. 7,806,295 discloses a dose indicator driven by a flexibletab attached to a ring. U.S. Pat. No. 5,421,482 discloses a mechanicaldose indicator driven round by a ring of flexible arms on a rigid plate.WO-A-2006/119766 discloses a pMDI dose indicator comprising a singlecomponent for use with an unconventional rotary metering valve; therebyrequiring modifications to the pMDI inhaler unit or to the actuator inwhich it is mounted.

U.S. Pat. No. 6,679,251 discloses a bottom-mounted pMDI dose counterwhich incorporates two C-springs the serve both to reset the dosecounter and to provide follow-through for the valve firing of theinhaler. WO-A-02/91293 discloses a counter mechanism operated by acollapsible flexible ‘spider’.

SUMMARY OF THE INVENTION

Each of the dose indicators or dose counters described above tends toinvolve features that would build expense into the finished design, andcannot be considered suitable for use in price-sensitive markets.

One drawback with existing dose indicators is the number of componentsrequired for their construction. In some cases, there may be in excessof six components in the dose indicator. This tends to make such doseindicators expensive to manufacture both in terms of component cost andoverall material cost. In addition, due to the number of components,there are substantial assembly costs.

Another drawback is the stack-up of dimensional tolerances of thecomponents of the dose indicator. If many components are required tomanufacture the dose indicator, the tolerance of each component needs tomore predictable to ensure that the dose indicator operates as intended.This involves significant development time to optimise the dimensionsand means that the number of components has an effect on the accuracyand reliability of the dose indicator during operation. There are alsoissues with combining components that have dimensions at the edge oftolerance, to ensure that the total stack of tolerances does not impedeperformance and that acceptable combinations are not unduly rejected.There are also issues with combining components that are at the edge oftolerance, to ensure that the total stack of tolerances does not impedeperformance and that acceptable combinations are not unduly rejected.There are also issues with combining components that are at the edge oftolerance, to ensure that the total stack of tolerances does not impedeperformance and that acceptable combinations are not unduly rejected.

The issue of cost is a particular concern when considering doseindicators for highly price-sensitive markets, for example, Asia.

The present invention seeks to provide a dose indicator that can bemanufactured at low cost so that it becomes an attractive propositioneven in price-sensitive markets. Here and in the following description,the term “dose indicator” is intended to refer to both dose counterdevices and dose indicator devices.

It has been recognised that in order to provide a dose indicator thatcan be manufactured at low costs, it would be desirable to provide adose indicator that has fewer components.

Further it is desirable to provide an inexpensive, simple and reliabledose indicator that would be compact in size so that it could, at thesame time, be inserted or fitted into a housing of a typical commercialinhaler, in particular into an actuator of a pressure-actuated metereddispensing device of similar shape and comparable size to existing,commercial actuators.

In accordance with a first aspect of the present invention, there isprovided a dose indicator for a pressure-actuated metered fluiddispensing device, the dose indicator comprising:

a chassis element having a viewing portion;

a display element located within the chassis element;

a resilient deformable element; and

an indexing element having an axis, translation of the indexing elementalong its axis from a first position to a second position causingdeformation of the resilient deformable element in the same direction astranslation of the indexing element resulting in generally greaterdisplacement of portions of the resilient deformable element nearer tothe axis relative to portions thereof further from the axis, thedisplacement of the portions of the resilient deformable element in thesame direction as translation of the indexing element inducing indexingof the display element from a current position to a subsequent positionrelative to the viewing portion of the chassis element.

It is to be recognised that the phrase “resulting in generally greaterdisplacement of portions of the resilient deformable element nearer tothe axis relative to portions thereof further from the axis” is to beunderstood that, in each instance, a generally greater displacementoccurs nearer to the axis than further away from the axis. Preferably,the outline shape of the resulting displacement of the resilientdeformable element is symmetrical about the axis. More preferably, theresulting outline shape may be an inverted frustum of a cone.

In one embodiment of the invention, the elements of the dose indicatorare advantageously formed in a maximum of three components. In anotherembodiment, the dose indicator advantageously comprises only twocomponents. By substantially reducing the number of components, theoverall cost of a dose indicator in accordance with the presentinvention is substantially reduced. In addition, a dose indicator inaccordance with the present invention can simply be slotted over anozzle block in an actuator for a pressure-actuated metered dispensingdevice.

Preferably, the resilient deformable element is arranged around the axisof the indexing element. Ideally, the display element is also arrangedaround the axis of the indexing element. By having the resilientdeformable element and the display element arranged around the axis ofthe indexing element, the components can easily be aligned with respectto the actuator in which the dose indicator is to be located and withrespect to the associated pressure-actuated metered dispensing device.Preferably, the dose indicator is designed such that, when it isassembled into a pressure-actuated metered fluid dispensing device, theaxis of the indexing element coincides with the central vertical axis ofa stem socket or nozzle block of the pressure-actuated metered fluiddispensing device.

The display element may comprise a continuous display ring or adiscontinuous display ring. By having the display element in the form ofa display ring, the dose indicator can easily be indexed with respect tothe housing in which it is located.

In one embodiment, the display element may comprise a disc centred aboutthe axis of the indexing element. Again, this provides inherentalignment of the display element with respect to the indexing element.

Preferably, the indexing element comprises a tube element connected tothe resilient deformable element.

Advantageously, the resilient deformable element comprises a grilleelement. A further grille element may be located adjacent the resilientdeformable grille element so that it substantially abuts the resilientdeformable grille element in the first position to restrict the passageof air through the abutting grille elements.

When the indexing element is in the second position, the resilientdeformable grille element is spaced from the further grille element toallow the passage of air through the spaced apart grille elements. Thecooperation between the deformable grille element and the further grilleelement advantageously ensures that the user is able to coordinate theirinspiratory breath with their actuation of the pressure-actuated metereddispensing device. Moreover, such embodiments advantageously allow forthe provision of a dose indicator that includes breath coordinationfunctionality without increasing the overall cost of the dose indicator.

The further grille element may be associated with one of: the displayelement and the chassis element. In this case, the resilient deformablegrille element is preferably associated with the other one of: thedisplay element and the chassis element.

In one embodiment of the present invention, the chassis element maycomprise a housing including a base portion and a lid portion, the baseportion including the indexing element and the resilient deformablegrille element. The lid portion is desirably connected to the baseportion by a living hinge, and is closable with respect to the baseportion.

This arrangement of the chassis element provides an effectivelyself-contained unit that can simply be inserted into an actuator of thepressure-actuated metered dispensing device, fitting into position overa stem socket or nozzle block in the housing.

Preferably, the base portion comprises a wall portion having the viewingportion formed therein. This viewing portion is desirably aligned with awindow provided in the actuator of the pressure-actuated metered devicewhen the dose indicator is inserted therein.

Advantageously, the housing forming the chassis is formed as onecomponent.

In one embodiment, the display element may comprise the further grilleelement mentioned supra and be housed within the housing. The furthergrille element may be substantially rigid or it may be fixed. A rack maybe formed on a portion of the display element by which it is indexedwith respect to the viewing portion.

Advantageously, in embodiments in which the display element comprisesthe further grille element, the display element and further grilleelement are formed as one component.

In order to implement the indexing of the display element with respectto the viewing portion, desirably the housing further comprises a wormelement arranged to engage with the rack formed on the display element,rotation of the worm element indexing the display element with respectto the viewing portion.

It is preferred that the worm element comprises a plurality of teethlocated on at least a portion thereof. The worm element may comprise anaxle portion at each end, the plurality of teeth being located betweenthe two axle portions. Advantageously, a locking pawl is provided forengaging with at least one tooth formed on the worm element.

Ideally, the worm element is supported by first and second supportmembers formed on the chassis element, the first and second supportmembers advantageously being integrally formed with the lid portion.Advantageously, the first and second support members each have athrough-hole to receive an end of the worm element, the through-holesbeing moulded using an injection moulding tool that opens along an axissubstantially perpendicular to an axis defined by the centres of thethrough-holes.

Advantageously in those embodiments including a base portion, anadvancement arm is provided in the base portion which is operable torotate the worm element as the indexing element moves between the firstand second positions. Preferably, the advancement arm and the baseportion are integrally formed.

The spacing of the rack preferably corresponds to the flight of the wormelement.

In a further embodiment, the lid portion may include at least oneadditional spring arm that engages with a hole provided in the side ofthe indexing element. This provides a restorative upward force to theresilient deformable element even in its rest position.

In alternative embodiments to those where the chassis element comprisesa housing including a base portion and a lid portion, the base portionincluding the indexing element and the resilient deformable grilleelement, the chassis element may favourably comprise an inner wallportion and an outer wall portion joined by a rim portion, the inner andouter wall portions defining an annulus therebetween, the displayelement being mounted within the annulus with a portion of the displayelement being visible through the viewing portion formed in the outerwall portion.

Preferably, the chassis element includes a first set of chassis elementteeth located within the annulus adjacent the rim portion and a secondset of chassis element teeth associated with the outer wall portion andspaced from the rim portion. In addition, the outer wall portion maycomprise a plurality of clip elements extending therefrom on which thesecond set of chassis element teeth is formed. Moreover, the first andsecond sets of chassis element teeth face one another and are integrallyformed with the chassis element. Advantageously, the first and secondsets of chassis element teeth are offset with respect to one another. Ina similar way to the other embodiments, the chassis element isadvantageously formed as one component.

In such embodiments, the display element may comprise first and secondsets of display element teeth located on respective peripheral edgesthereof, the first and second sets of chassis element teeth engagingwith respective ones of the first and second sets of display elementteeth in accordance with the first and second positions of the indexingelement. In such embodiments, the display element may comprise theresilient deformable grille element and the indexing element, theresilient deformable grille element connecting the display element tothe indexing element.

The display element is preferably formed as one component.

In addition, in such embodiments, translation of the indexing element tothe second position favourably causes engagement of the second set ofchassis element teeth with the second set of display element teeth torotate the display element through a fraction of an indexing pitch in afirst direction, and translation of the indexing element back to thefirst position causes engagement of the first set of chassis elementteeth with the first set of display element teeth to rotate the displayelement through a remaining fraction of the indexing pitch in the firstdirection.

In such embodiments, the chassis element may further comprise a chassiselement spring arranged to maintain engagement of the first set ofchassis element teeth with the first set of display element teeth whenthe indexing element is in the first position. In addition, the chassiselement spring may comprise the further grille element, the chassiselement spring being connected to the inner wall portion.

In accordance with another aspect of the present invention, there isprovided a pressure-actuated metered dispensing device comprising: anactuator portion; a window formed in the actuator portion; a dispensingportion; a nozzle block located between the actuator portion and thedispensing portion; a dose indicator as described above, the indexingelement being aligned with the nozzle block and the viewing portionbeing aligned with the window in the actuator portion; and a canistercomprising a container and a metering valve housed within the actuatorportion, the metering valve having a valve stem that engages the nozzleblock and wherein, in use, relative movement of the container and thenozzle block causes the translation of the indexing element from thefirst to the second position as a result of engagement of a portion ofthe canister and the indexing element.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference will nowbe made, by way of example only, to the accompanying drawings in which:

FIG. 1 illustrates an isometric top view of an exemplary actuator for apMDI inhaler without a dose indicator;

FIG. 2 is similar to FIG. 1 but illustrates an isometric sectioned topview of an exemplary actuator for a pMDI inhaler;

FIG. 3 is similar to FIG. 1 but illustrates an exemplary dose indicatorof the present invention located within the actuator;

FIG. 4 illustrates an isometric top view of a dose indicator inaccordance with a first exemplary embodiment of the present invention;

FIG. 5 illustrates an isometric top view of the dose indicator shown inFIG. 4 but with its lip open;

FIG. 6 illustrates a sectioned side view of the dose indicator shown inFIG. 5;

FIG. 7 illustrates a chassis element in accordance with the firstexemplary embodiment of the present invention;

FIG. 8 illustrates an isometric top view of a worm element in accordancewith the first exemplary embodiment of the present invention;

FIG. 9 illustrates an isometric top view of a display element inaccordance with the first exemplary embodiment of the present invention(display numerals not being shown);

FIG. 10 illustrates a sectioned side view of the dose indicator inaccordance with the first exemplary embodiment of the present inventionwith its lid partially open;

FIG. 11 illustrates a sectioned side view of the dose indicator inaccordance with the first exemplary embodiment of the present inventionwith its lid closed;

FIG. 12 illustrates another sectioned side view similar to that of FIG.11, but illustrates the engagement of the worm element with an indexingarm;

FIG. 13 illustrates a sectioned side view of the dose indicator inaccordance with the first exemplary embodiment of the present inventionmounted within a actuator of a pMDI inhaler;

FIG. 14 illustrates a sectioned isometric view of a pMDI inhaler havinga dose indicator in accordance with the first exemplary embodiment ofthe present invention;

FIG. 15 illustrates a sectioned side view of a chassis element inaccordance with the first exemplary embodiment of the present inventionin its second or displaced position;

FIG. 16 illustrates a cross-section of a dose indicator in accordancewith the first exemplary embodiment of the present invention with theindexing element in its first or rest position;

FIG. 17 is similar to FIG. 16 but illustrates the indexing element inits second or displaced position;

FIG. 18 illustrates a partial isometric top view of a chassis element inaccordance with a second exemplary embodiment of the present invention,the lid not being shown for clarity;

FIG. 19 is similar to FIG. 18 but also illustrates the display ringwithin the chassis element;

FIG. 20 is similar to FIG. 19 but also illustrates the worm element;

FIG. 21 illustrates an isometric top view of the lid part only of thechassis element in accordance with the second exemplary embodiment ofthe present invention;

FIG. 22 illustrates an isometric top view of the assembled doseindicator in accordance with the second exemplary embodiment of thepresent invention;

FIG. 23 illustrates an isometric top view of a dose indicator inaccordance with a third exemplary embodiment of the present invention;

FIG. 24 illustrates an isometric bottom view of a dose indicator inaccordance with the third exemplary embodiment of the present invention;

FIG. 25 illustrates an isometric top view of a chassis element inaccordance with the third exemplary embodiment of the present invention;

FIG. 26 illustrates an isometric bottom view of a chassis element inaccordance with the third exemplary embodiment of the present invention;

FIG. 27 illustrates an isometric top view of a display element inaccordance with the third exemplary embodiment of the present invention(not all display numerals being shown);

FIG. 28 illustrates an isometric bottom view of the display element ofFIG. 27 (display numerals not being shown);

FIG. 29 illustrates a sectioned isometric top view of the dose indicatorin accordance with the third exemplary embodiment of the presentinvention in its first or rest position;

FIG. 30 is similar to FIG. 29 but illustrates the display ring andviewing window;

FIG. 31 is similar to FIG. 29 but illustrates the dose indicator in itssecond or displaced position; and

FIG. 32 illustrates a sectioned isometric top view of the assembled doseindicator in accordance with the third exemplary embodiment of thepresent invention mounted within a pMDI actuator.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with respect to particularexemplary embodiments and with reference to certain drawings but theinvention is not limited thereto. The drawings described are onlyschematic and are non-limiting. In the drawings, for illustrativepurposes the size of some of the elements may be exaggerated and notdrawn to scale.

It will be understood that the terms “vertical”, “horizontal”, “top”,“bottom”, “above”, “below”, “left”, “right” etc. as used herein refer toparticular orientations of the Figures and these terms are notlimitations to the specific embodiments described herein.

As mentioned above, in addition to reducing the cost of a dose indicatorfor use with pMDI inhalers, it is desirable to provide a dose indicatorthat includes breath coordination functionality without increasing theoverall cost of the dose indicator. The exemplary dose indicators shownin FIGS. 4 to 31 include such breath coordination functionality. Howeveras described below, if desired or needed, these dose indicators can besimply modified in such a manner that this functionality is removed,while still maintaining an advantageous inexpensive, simple and reliabledose indicator.

Before turning to the exemplary embodiments, breath actuation andcoordination are described in the following paragraphs to ensure aproper understanding of the breath coordination functionality of theexemplary embodiments.

Many users of pMDI inhalers find it difficult to time correctly themoment at which they actuate their pMDI inhaler relative to the momentat which they start to inhale. Further, a significant number of otherusers do not realise that they have a problem with coordinating theirin-breath with the actuation of the pMDI inhaler and therefore do notrealise that they are not receiving an optimum dose each time.Naturally, not being able to have the correct coordination leads to nothaving optimum treatment as possibly a large percentage of each dose isnot inhaled. Accordingly, there is a general ongoing need for many pMDIusers to have an inhaler that maximises the dose of the particular drugbeing delivered to their lungs via their inhaled inspiratory breath.

There are currently two main solutions to this problem, namely, breathactuation where a triggering mechanism utilises the inhalation of a userto release the pMDI valve; and breath coordination where the inhalationand the release of the dose are timed to coincide in some other way. Theformer solution (“breath actuation systems”) tends to involve complex(and therefore expensive) mechanisms, whilst the latter solution(“breath coordination systems”) can be much simpler and thereforecheaper.

Many breath coordination systems fit into one of two categories: “can'tinhale until press” and “can't press until inhale”. The former categorytypically involves air passageways through the inhaler that only openwhen the user pushes down on the pMDI canister (the assembly comprisingthe container and metering valve). In the latter category, it is notpossible to press the pMDI inhaler downwards until some mechanicalobstruction has been removed as a consequence of inspiration (e.g. hadbeen unblocked by movement of a breath-operated obstructive vane). Thusinhalation by the patient effectively allows movement of the containerto operate a dispensing valve associated with the container.

It should be appreciated that many prior art dose indicators are notcompatible with the inspiratory systems mentioned above, nor provide amechanism in themselves for breath actuation or coordination.

As will be explained in detail below, certain advantageous embodimentsof dose indicators in accordance with the present invention include anintegrated breath coordination system of the “can't inhale until press”type of operation. This operation will be described in more detailbelow.

Referring initially to FIGS. 1 and 2, an exemplary actuator 100 for apMDI inhaler (the inhalation canister not being shown) is shown. Theactuator is similar in size and shape to many marketed pMDI actuators.The actuator 100 comprises a tubular housing portion 110 and a tubularmouthpiece portion 120. At the closed bottom end of the tubular housingportion 110 sits a nozzle block 130 that comprises a stem socket 140 inflow communication with a sump region 150 and an exit orifice 160. Atthe back of the tubular housing portion 110 is a viewing window 170. Atthe bottom of the actuator 100 is a thumb grip 180. An actuator runningsurface 190 is provided adjacent to the lower end of the tubular housingportion 110.

FIG. 3 is similar to FIG. 1 but illustrates a display element 200 thatis visible through the viewing window 170 of the actuator 100. Thedisplay element 200 forms part of a dose indicator in accordance withthe present invention. As will be described in more detail below, thedisplay element may comprise a ring (not shown), in particular acontinuous ring or a discontinuous ring, or alternatively a disc.

In accordance with a first exemplary embodiment of the presentinvention, the dose indicator 300 comprises three principal components,namely, a chassis element 310, a display element 320 and a worm element330. It is intended for use with a pMDI inhaler actuator 100, forexample, as described with reference to FIGS. 1 to 3 above, and a pMDIcanister as will be described in more detail below with respect to FIG.14. The form and use of such a pMDI canister will be familiar to thoseskilled in the art.

Referring now to FIGS. 4 to 12, the exemplary dose indicator 300 isshown in more detail. The chassis element 310 which has a generallyrigid outer wall 340, joined via a living hinge 350 to a lid 360. At twopoints on the outer wall 340, flexible clips 370 are provided that serveto engage with two corresponding tabs 380 on the periphery of the lid360. This engagement retains the lid in its closed position afterassembly, as shown in FIG. 4. The underside 390 of the lid 360 alsobears two support posts 400, 405 with lateral through-holes 410, 415(FIG. 7) that serve as bearings for an axle 420 of the worm element 330.The support posts 400, 405 are angled outwardly towards their ends suchthat the through-holes 410, 415 may be injection moulded using toolingthat needs no side-draw actions, thereby reducing moulding toolcomplexity and cost and minimising moulding cycle times. Between the twosupport posts 400, 415 is located a locking pawl 440 for engagement withthe worm element 330.

Within the outer wall 340 is an annular resilient deformable grilleelement 450 that comprises a series of rings 460 linked by radialmembers 470. The rings 460 and radial members 470 define slots 480. Theinside part of the annular resilient deformable grille element 450extends upwards as a central alignment tube or a tubular indexingelement 490, with a central aperture 500 in which may be located thehollow male stem of the pMDI valve (not shown) when the pMDI canister isassembled into the actuator 100 with the assembled dose indicator 300.

A hooked cantilevered advancement arm 510 is mounted near the inner edge(shown as 660 in FIG. 12) of the annular resilient deformable grilleelement 450 for engagement with the worm element 330 as will bedescribed in more detail below. A viewing portion 520 in the form of acut-out is provided in the outer wall 340 of the chassis element 310through which the display element 320 can be seen when assembled.Further lid tabs 530 are provided which sit within respective recesses540 formed in the outer wall 340 as is shown more clearly in FIG. 4.

FIG. 8 illustrates the worm element 330 in more detail. As shown, theworm element 330 comprises a plurality of drive teeth 550 arrangedaround its periphery in a central region between the ends of the axle420. In this exemplary embodiment, there are eight drive teeth 550 whichare intersected by a single-turn worm flight 560 formed in a centralportion of the worm element 330.

With reference to FIG. 9, the display element 320 comprises a displayring 570 in the form of a cylindrical tubular wall, the outside of whichbears numerals (for example, 200, 190, 180 . . . ; not shown)corresponding to the remaining number of doses of medicament in thecontainer of the pMDI canister. Extending in from the bottom end of thedisplay ring 570 is a substantially rigid grille element 580 in the formof rings 590 linked by radial members 600, the rings 590 and radialmembers 600 defining slots 610. A central aperture 620 is formed by theinner edge of the grille element 580. A series of teeth in the form of arack 625 is mounted on the top surface of one ring of the grille element580.

FIGS. 5, 6 and 10 to 12 illustrate respective positions of the lid 360with respect to the outer wall 340 as it is moved from an open position(FIGS. 5 and 6) to a fully closed position (FIGS. 11 and 12).

The exemplary dose indicator 300 is assembled as follows. Referring toFIGS. 4 to 9 in particular, the ends of the axle 420 of the worm element330 are pushed into the through holes 410, 415 provided in respectiveones of the two support posts 400, 405. This is done by pushing the wormelement 330 towards the underside 390 of the lid 360 so that the supportposts 400, 405 flex outwardly by a sufficient amount to allow the axle420 to click into place within the through holes 410, 415, as shown inFIG. 5. The display element 320 is placed into the chassis element 310,as shown in FIG. 5, being pushed over the hooked end of the advancementarm 510, which transiently deflects inwardly to allow it to pass throughthe central aperture 620 in the grille element 580 of the displayelement 320. Care is taken to ensure, for example, by an automatedvision recognition system and/or by the provision of alignment features(not shown), that the display element 320 is orientated correctly sothat it displays the correct count numerals (e.g. “200”) as seen throughthe viewing portion 520 of the chassis element 310. The dose indicatoris now in the part-assembled state shown in FIGS. 5 and 6.

The final step of this very simple assembly procedure is to close thelid 360, as is shown in the sequence of FIGS. 5 and 6 (lid fully open),FIG. 10 (lid partially closed), and FIGS. 11 and 12 (lid fully closed).This movement of the lid 360 is made possible by the presence of theliving hinge 350 that joins the lid 360 to the outer wall 340 of thechassis element 310. As the lid 360 reaches its fully closed positionwithin the top of the outer wall 340, as shown also in FIG. 4, the lidtabs 380 formed on the lid 360 engage with the flexible clips 370 formedon the outer wall 340, thereby locking the lid 360 into its fullyassembled position. In the fully assembled position, the two additionalalignment tabs 530 on the lid 360 engage with corresponding recesses 540in the top of the outer wall 340. The worm flight 560 of the wormelement 330 is now engaged with the teeth of the rack 625 of the displayelement 320 as shown in FIGS. 12 and 13.

Use and operation of the exemplary dose indicator may best be understoodwith reference to FIGS. 11 to 17.

Once assembled, the dose indicator 300 is then pushed into the actuator100 and over the nozzle block 130 (FIG. 2), to reach the position shownin FIG. 13. As shown in FIG. 13, the outer wall 340 of the doseindicator 300 sits within the base of the tubular housing portion 110 ofthe actuator 100 with the viewing portion 520 of the outer wall 340aligned with the window 170 of the actuator 100. Desirably, the window170 is large enough for the user to see up to two sets of numerals, forexample, ‘120’ and ‘110’, so that both are visible when the actual countcorresponds to an intermediate number, for example, ‘116’ or ‘115’. Inthis manner, the user can observe the shifted position of the displayand can appreciate that the number of doses remaining has beendecreased, for example, from one hundred and sixteen doses to a hundredand fifteen doses remaining The indexing element 490 sits around thenozzle block 130, and is free to move axially upwards and downwards acertain distance with respect to the nozzle block 130 by virtue of theflexibility of the deformable grille element 450.

After the dose indicator 300 has been located within the actuator 100, aconventional pMDI canister (FIG. 14) is inserted into the stem socket140 of the nozzle block 130 through the aperture 500 of the indexingelement 490 as shown in FIG. 14. A valve stem 640 associated with ametering valve on the container 630 is engaged with the nozzle block130. Movement of the valve stem 640 towards the body of the container630 opens the valve to dispense a metered amount of medicament. Thecombination of the pMDI container 630 and its associated metering valvetogether with the dose indicator 300 and actuator 100 is referred tohereinafter as the pMDI inhaler 650.

Downward pressure on the container 630, in the direction of arrow ‘A’,causes the valve stem 640 to open the associated valve allowing ametered amount of medicament to pass through the exit orifice 160 andinto the mouthpiece 120 (see also FIG. 2). It is this downward pressureand opening of the valve to dispense a metered amount of medicament thatneeds to be indicated by the dose indicator 300 in accordance with thepresent invention.

When the user requires a dose of medicament, he/she takes his/her pMDIinhaler 650 and places the mouthpiece 120 within his/her mouth. Torelease a dose of medicament, the user then presses down upon the freeend 635 of the container 630 (FIG. 14), whilst at the same time pressingupwards against the thumb grip 180, thereby causing the container 630 tomove downwardly with respect to the valve stem 640. This movementdischarges the aerosolised dose via the exit orifice 160 and mouthpiece120 into the mouth and lungs of the user. The user then releases thedownward force applied to the top 635 of the container 630, allowing itto return upwards relative to the valve stem 640 under the influence ofan internal compression spring (not shown) associated with the valve.

The dose indicator 300 registers the released dose as follows. As thecontainer 630 moves downwards during user actuation, the lower surface633 of a ferrule 645 of the valve pushes down against the top of theindexing element 490, causing it to move downwards relative to the outerwall 340, lid 360, display element 320 and worm element 330 of the doseindicator 300. This movement is made possible by the transient downwardsdisplacement of an inner part 660 of the deformable grille element 450as the grille element 450 elastically deforms. This is best shown inFIGS. 15 to 17.

FIG. 16 shows the situation where the dose indicator 300 is in its restposition, with the deformable grille element 450 in a non-deformed stateand the indexing element 490 in an upward or first position. FIGS. 15and 17 show the indexing element 490 pushed downwardly, away from thelid 360, the deformable grille element 450 having become transientlydeformed as a consequence of this downward movement.

Turning now to FIG. 12, as described above the advancement arm 510 ismounted on the inner part 660 of the deformable grille element 450, andthus it will move downwardly with the indexing element 490 as it ispushed down. As the advancement arm 510 is pushed downwards, a hook 515at its upper end engages with one of the drive teeth 550 on the wormelement 330, causing the worm element 330 to rotate clockwise as shownin FIG. 12. As there are eight teeth in this embodiment of the wormelement 330, the clockwise rotation is approximately 45°. Any excess“follow through” motion of the container 630 and indexing element 490,for example, as a result of dimensional tolerances/variation, will notaffect operation of the dose indicator 300 as the advancement arm 510 isfree to continue downwards once it has rotated and disengaged the teeth550 of the worm element 330. The rotational movement of the worm element330, in turn, rotates the display element 320 as the worm flight 560engages with and drives the teeth of the rack 625 on the display element320, the spacing of the teeth of the rack 625 corresponding to theflight of the worm element 330. The amount of rotation of the displayelement 320 will not be great, however, due to the gearing provided bythe use of such a worm and rack arrangement. Nevertheless, the numerals(not shown) displayed via the window 170 of the actuator 100 and viewingportion 520 of the chassis element 310 to the user will move slightly,and, after multiple successive doses, the displayed numerals willchange, for example, from “200” to “190”, indicating a reduction of tenin the remaining number of medicament doses available to the user.

The gearing also serves to ensure that the display element 320 cannotreadily be inappropriately rotated without discharging a dose, eitherforwards or backwards, by user intervention, for example, by insertingsomething through the window 170 of the actuator 100 and viewing portion520 formed in the outer wall 340.

Completing the actuation cycle, the resilient deformable grille element450, having deflected elastically, will act as a spring when it isreleased, serving to return the indexing element 490 back up to its restor first position when the user stops pressing on the container 630 ofthe pMDI canister. The deformable grille element 450 will thereforereturn from the position illustrated in FIG. 17 to that illustrated inFIG. 16 once the pressure is released.

The advancement arm 510 accordingly also returns to its owncorresponding rest position. The worm element 330 cannot, however,rotate back to its previous position, as the locking pawl 440 (FIG. 11)engages with its teeth 550 and prevents any rotation. The hook 515 atthe end of the advancement arm 510, meanwhile, returns past the wormteeth 550 by deflecting past them back to its first or rest position asshown in FIG. 12.

At the end of life, that is, for a displayed count of ‘0’, anend-of-life stop feature (not shown) provides a restraint on furtherdose indicator display rotation. This feature could take several forms,such as missing teeth, filled in teeth, a raised boss or other feature,etc. in the display ring.

As will be seen from FIG. 16, in its rest position, the rings 460 of thedeformable grille element 450 abut and occlude the slots 610 between therings 590 of the grille element 580 of the display element 320, therebyproviding a significant resistance to the inhalation of air through theslots of the grille elements 450, 580 by a user. By ensuring that theouter contours of the chassis element 310 match the inner contours ofthe actuator 100, bypass air leaks round the outside of the doseindicator can be minimised. When the container 630 is pushed downwardly,causing the indexing element 490 of the dose indicator 300 to bedisplaced downwardly as shown in FIG. 17, the rings 460 of thedeformable grille element 450 move away from the slots 610 between therings 590 of the grille element 580 of the display element 320, therebysignificantly reducing the resistance to airflow. The sudden reductionof resistance effectively allows inhalation to start. By this means, thegrille elements 450, 580 are able to provide a substantial measure ofbreath-coordination to the user.

By sucking on the mouthpiece 120 before depressing the container 630,the user is able to ensure that an inhaled airflow starts as the grilleelements 450, 580 move apart. Advantageously the pMDI valve releases adose of medicament while the grille elements 450, 580 are moving apart,preferably very soon after the inhaled airflow starts. This coordinationof timing essentially ensures that the emitted aerosol of medicamentparticles is inhaled early in the respiratory manoeuvre of the user andthus reaches the deeper parts of the lungs where the medicament is mosteffective. As a result, the dose indicator 300 described above alsoprovides a breath-coordination system for a user.

In alternative embodiments (not shown), the rings of the deformablegrille element 450 may be configured never to occlude the slots 610 ofthe other grille element 580, and/or bypass air channels can be providedbetween the chassis element 310 and the actuator 100, for example inconjunction with a continuous, non-perforated deformable grille element450. Such alternative embodiments serve to provide low cost doseindication with minimal changes to the inhaler actuator and a lowcomponent count, without breath coordination.

In a preferred embodiment, the indexing element 490 has a central axis670 passing through the centre of the central aperture 500 and extendingin a direction that is substantially perpendicular to the plane of thedeformable grille element 450 as shown in FIGS. 6, 10 to 12 and 15 to17. The central axis 670 also provides an alignment reference for thedisplay element 320 within the chassis element 310, for the deformationof the resilient deformable grille element 450 in the same direction asthe translation of the indexing element 490 from a first position (FIGS.11, 12 and 16) to a second position (FIGS. 15 and 17), and for thelocation of the dose indicator 300 on the stem socket 140 of the nozzleblock 130 (FIG. 1).

As shown in FIGS. 15 and 17, the deformation of the resilient deformablegrille element 450 forms an inverted frustrum of a cone which is centredabout the axis 670.

FIGS. 18 to 22 show a second exemplary embodiment of a dose indicator700 in accordance with the present invention. In general, this exemplaryembodiment is similar to the exemplary embodiment described above withreference to FIGS. 4 to 17 but differs from it in one principal way. Inorder to provide a greater return spring force than is provided by thedeformable grille element 450 alone, the second embodiment has twoadditional spring arms. In particular, these spring arms are arranged toprovide a restorative spring force even when the dose indicator is inits rest position, something which the deformable grille element 450does not provide.

It will be appreciated that the resilient deformable grille element 450of either the first or the second embodiment could be configured toprovide a restorative spring force when the dose indicator is in itsrest position. However, in such a configuration, it is difficult toensure that adequate resistance to air is provided in the rest position.This is due to having to mould the resilient deformable grille element450 in a non-planar form which becomes accurately and reliably planar inthe rest position of the dose indicator 300, 700. The deformable grilleelement 450 needs to be substantially planar when the dose indicator isat rest, in order to provide acceptably high initial resistance toinhaled airflow through the system.

Components that are the same in both the first and second exemplaryembodiments of the dose indicator 300, 700 are referenced the same.

FIG. 21 best shows the additional spring arms 710 (although they arealso visible in FIG. 22), which are formed integrally with lid 720.These arms 710 are configured so that their tips fit into holes 730provided in the sides of the indexing element 740. The lower part of theindexing element 740 has wings 745 protruding from diametricallyopposite regions. These allow through holes 730 to be formed in the sidewall of the indexing element 730 during injection moulding, without theneed for side-action tooling.

FIG. 22 shows the assembled dose indicator 700 of the second exemplaryembodiment, showing that the tips (not shown) of the additional springarms 710 are pushed into the holes 730. Although not readily evidentfrom this Figure, the two spring arms 710 are downwardly elasticallydeflected with generally greater downward deflection towards their tipsin this rest position of the dose indicator 700. This deflection causesa resultant upward force to be applied by the spring arms 710 to theindexing element 740, thereby providing a restorative upward force tothe deformable grille element 450, even in its rest position.

In FIGS. 18 to 22, the indexing element 740 of the dose indicator 700also has a central axis 670 passing through the centre of the centralaperture 500 and extending in a direction that is substantiallyperpendicular to the plane of the deformable grille element 450. Thiscentral axis provides an alignment reference for the display element 320within the chassis element 310, for the deformation of the resilientdeformable grille element 450 as it is deformed by translation of theindexing element 740 from a first position to a second position, and forthe location of the dose indicator 300 on the stem socket 140 of thenozzle block 130 as described above with reference to the firstexemplary embodiment of the dose indicator 300 (see FIG. 2).

In summary, the first and second exemplary embodiments in accordancewith the present invention each provide a simple dose indicator with aten-dose resolution that counts down inhaler actuations from 200 tozero. Their design is space-efficient and is compatible with inhalers offamiliar shape and size to users, and they each require only threeadditional components compared to a standard pMDI inhaler, therebymeeting the market need for sufficiently low cost. In addition, as shownby the illustrated exemplary embodiments, the design can also,advantageously, incorporate a built-in integrated breath coordinationsystem of the “can't breathe until press” type. In addition to theseadvantages and benefits, the dose indicator can clip together as arobust sub-assembly/module, reducing dimensional tolerance issues. Thedose indicator may preferably be designed to provide count-before-firereassurance, in order to minimise the possibility of under-counting. Ifthe user fails to ‘follow through’ to valve actuation after indexing thedose indicator, the dose indicator will indicate fewer doses remain thanis actually the case. This is deemed to be safer than the alternativewhere the user might actuate the valve to dispense a dose but might thenfail to follow through to register the count, that is, to index the doseindicator. In that case, the dose indicator might register moreremaining doses than is actually the case, leading to a potentiallydangerous situation where the user is led to believe they have moredoses left than there are in reality. Note that manufacturing tolerancesmean that it is never possible to guarantee that valve actuation anddose indicator advancement occur exactly simultaneously in anymechanical system: the choice has to be made which is designed to occurfirst.

The three elements of the dose indicator can be cheaply moulded, forexample, injection moulded, from “non-engineering grade” polymer, suchas a polyolefin such as polyethylene or polypropylene. Polypropylene ispreferred as it allows the creation of the living hinge as describedabove.

Turning now to a third exemplary embodiment of a dose indicator 800 inaccordance with the present invention, reference is made to FIGS. 23 to32. The dose indicator 800 is similar to the exemplary dose indicators300 described above in that it has a chassis element 810 with a viewingportion 820 through which a portion of a display element 830 can beseen. However, in this embodiment, the chassis element 810 and thedisplay element 830 are the only two components.

With reference to FIGS. 25 and 26 in particular, the chassis element 810comprises a generally rigid outer wall 840, joined via an upper rim 850to an inner wall 860. At multiple, in this embodiment six, locationsaround the outer wall 840 flexible clips 870 are formed which serve toretain the display element 830 when assembled. The bottom ends 875 ofthese clips 870 each bear two teeth 880. Similar teeth 890, but mountedfacing down rather than up, are provided in pairs on the underside ofthe upper rim 850, as may be seen in FIGS. 30 and 31. Apertures 900serve to allow injection moulding of the clips 870. As described above,a viewing portion 820 is provided in the outer wall 840 which alignswith the window 170 (FIG. 1) to enable viewing of the displayed count.As shown in FIG. 26, the chassis element 810 also includes a grilleelement 910 having grille slots 920 formed by rings 930 joined by radialmembers 935 in a similar way to the grille element 580 of the displayelement 320.

With reference to FIGS. 27 and 28 in particular, the display element 830comprises a rigid display ring 940, on the outer surface of which areprovided numerals 945 (not all shown in FIG. 27) corresponding tohundreds, tens and units digits of dose counts. For example, there maybe thirteen sets of these numerals, from ‘120’ down to ‘0’ in counts often (not all shown in the relevant Figures), arranged anti-clockwise asviewed from the top of the display element 830. At the bottom of thedisplay ring 940 is provided a set of lower teeth 950 and at the topthereof is provided a set of upper teeth 960.

The display ring portion 940 is connected to an indexing element or acentral alignment tube 970, for example, as may be seen more clearly inFIGS. 30 and 31, via a flat labyrinthine follow-through spring 980 (FIG.28). The follow-through spring 980 comprises spring slots 990 which aredefined by rings 1000 joined by radial members 1010 as shown. This issimilar to the deformable grille element 450 of the first exemplaryembodiment of the dose indicator 300 described above with reference toFIGS. 4 to 17.

Protruding downwards from the inside of the display element 830 arethree counter spring arms 1020 in the form of three bows, each springarm 1020 being joined at both ends rather than cantilevered (FIG. 28).These spring arms 1020 press against the actuator running surface 190(FIG. 1) and bias the upper sets of teeth 890, 960 into mutualengagement while separating the lower sets of teeth 880, 950 from oneanother. When the container is pushed downwards by a user, as describedabove, to release a dose of medicament formulation, the spring arms 1020flatten out against the running surface 190, they provide a resistiveforce that serves to separate the lower sets of teeth 880, 950 from oneanother and to bring the upper sets of teeth 890, 960 into mutualengagement to complete a complete unit decrement of the system, when theuser subsequently removes their downward pressure on the pMDI canister(not shown) as described above.

For a typically sized pMDI inhaler, the outside diameter of the displayring 940, and hence the display element 830, is approximately 23 mm. Fora 120-count display indicator, 132 teeth may typically be provided so asto allow for a few factory advancements/counts during assembly, plus anend-of-count stop feature location, etc. For a 23 mm diameter ring and132 teeth, each tooth would occupy 360°/132, that is approximately 2.7°,of the circumference, or approximately 0.55 mm. Such teeth are largeenough to be reliably injection moulded. As shown in FIG. 28, the samenumber of teeth are provided in the upper set of teeth 960 and the lowerset of teeth 950 but the upper set is offset with respect to the lowerset.

It is, however, preferable not to provide all 132 teeth. Instead, asshown in FIGS. 24, 27 and 28, only alternate teeth are provided in boththe upper and lower sets of teeth on the display ring 940. This has theadvantages of being easier to mould (the moulding tooling does not needsuch fine metal features), and also of avoiding the small dirt trapsbetween teeth that a full set of 132 teeth would create. By havingalternate teeth that are offset between the upper set and the lower set,lower frictional forces tend to be experienced.

As can be seen in FIGS. 24 and 26, the teeth 880 on the chassis element810 are also not immediate neighbours. In this case, two consecutiveteeth are “missing”, meaning that the pairs of teeth provided, that is,the bottom teeth 880 on the chassis clips 870, each comprise teeth thatare three positions apart. Because these are an odd number of teethpositions apart, then one of the pair will always be engaged with one ofthe teeth of the display element 830. In other words, the displayelement 830 and the display ring 940 will be rotated by a singleincrement of approximately 2.7° for each dose taken, even though not allthe 132 nominal teeth are present in any of the sets of teeth.Hereafter, where a pitch of one tooth is referred to, it will beunderstood to correspond to a single increment of the display ringdespite any missing teeth.

As described above with reference to the first exemplary embodiment, theindexing element 970 has an axis (not shown) about which the displayring 830 and the chassis element 810 are arranged.

The arrangement of the assembled components is as follows. The displayelement 830 sits in the annular gap between the inner wall 860 and theouter wall 840 of the chassis element 810, and is held loosely captiveby the bottom ends of the clips 870 of the chassis element 810. Thechassis element 810 is, in turn, retained in place near the bottom ofthe actuator 100 so that it is correctly rotationally aligned and it isprevented from rotational movement relative to the actuator 100.Appropriate clipping features (not shown) may be provided, for example,undercut clipping features can be moulded into the actuator 100 viamoulding tool side-core actions at the mouthpiece 120 and window 170.The pMDI canister (not shown) is a simple push-fit into the actuator100, with a valve stem associated with the valve pushing into the stemsocket 140 of the nozzle block 130. The ferrule of the valve (not shown)is arranged to sit adjacent to the upper end of the central alignmenttube or indexing element 970 of the display element 830 in the assembleddose indicator 800.

In use, the user actuates the inhaler by pressing down on the pMDIcanister (not shown), by squeezing their thumb and finger(s) togetheragainst the canister base and the thumb grip 180. This action tends topush the container of the pMDI canister down relative to the valve stemof the metering valve (not shown), which is restrained in the stemsocket 140 of the actuator 100. As the user continues to press, theferrule of the valve contacts the central alignment tube or indexingelement 970 if the two were not already in contact. As the valvecontinues to move downwards, it causes the counter spring arms 1020 toflex, these being less stiff than the follow-through spring 980. As thecounter spring arms 1020 flex, they allow the lower teeth 950 of thedisplay ring 940 to engage with the lower teeth 880 of the chassiselement 810, the full engagement of which causes the display element 830and display ring 940 to rotate by approximately half the pitch of theteeth in a clockwise direction as viewed from above.

With the teeth now fully engaged, further user depression of thecontainer of the pMDI canister towards the thumb grip 180 does notresult in any further motion of the display element 830, either axiallyor rotationally, as the engaged lower teeth 880, 950 will not allow it.The follow-through spring 980, however, is able to flex (as will bedescribed later) to allow further ‘follow-through’ motion of thecontainer of the pMDI canister relative to the stem socket 140. Thevalve stem (not shown) thus moves further inwardly relative to the restof the metering valve, and this (in ways familiar to those skilled inthe art) causes the valve to dispense a metered dose of medicamentformulation out via the bore of the valve stem, into the sump 150,through the exit orifice 160, and into the mouthpiece 120, as shown inFIG. 32, for inhalation by the user.

In this manner, with the counter spring arms 1020 being less rigid thanthe follow-through spring 980, ‘count before fire’ is assured, that is,the display element 830 increments before the valve dispenses a dose.Therefore, if the user fails to ‘follow through’ to valve actuationafter the display element 830 and display ring 940 has been incremented,the dose indicator will indicate that fewer doses remain than isactually the case. This is deemed to be safer than the alternative wherethe user might actuate the valve to dispense a dose but might then failto follow through to register the count, that is, to increment the doseindicator, as described above.

After receiving the dose, the user then relaxes their grip on the pMDIcanister (not shown) and thumb grip 180. This allows the follow-throughspring 980 to start to relax, which in turn allows the weaker counterspring arms 1020 to relax. As the springs relax, the counter spring arms1020 push the set of lower teeth 950 on the display ring 940 out ofengagement with the lower teeth 880 of the chassis element 810 and thenpush the upper set of teeth 960 into engagement with the upper teeth 890of the chassis element 810. The full engagement of the upper teeth 890,960 causes the display element 830 and display ring 940 to rotate by afurther approximately half tooth pitch in a clockwise direction asviewed from above. When the user completely releases the system, it hasbeen returned to its starting point except that a dose has been releasedand the display element 830 and display ring 940 of the dose indicator810 has now been rotated by the pitch of one tooth in a clockwisedirection as viewed from above. A spring (not shown) inside the pMDImetering valve resets the valve, in a manner that will be apparent toone skilled in the art. The numerals 945 displayed in the window 170 ofthe actuator 100 have thus moved in a downwards-counting direction, forexample, from a displayed count of ‘120’ in the direction of ‘110’.

After this process has been repeated ten times, that is, ten consecutivedoses have been dispensed, the displayed numerals will have moved by tentimes the pitch of the teeth, corresponding to the distance between setsof numerals 945 on the display ring 940 of the display element 830. Forexample, the displayed count might have moved from ‘120’ to ‘110’. Asdescribed above, the window 170 is large enough for the user to see upto two sets of numerals, e.g. ‘120’ and ‘110’, so that both are visiblewhen the actual count corresponds to an intermediate number, e.g. ‘116’or ‘115’. In this manner, the user can observe the shifted position ofthe display ring 940 and can appreciate that the count has gone from,for example, a hundred and sixteen doses remaining to a hundred andfifteen doses remaining

Although the display element 830, and hence the display ring 940, hasbeen described as being indexed a half pitch on translation of theindexing element from the first position to the second position and ahalf pitch on the return from the second position to the first position,it will be appreciated that any suitable fraction of the pitch betweenthe teeth can be implemented during the movement from the first positionto the second position with the remaining fraction of the pitch beingimplemented on the return from the second position to the firstposition.

At the end of life, that is, a displayed count of ‘0’, an end-of-lifestop feature (not shown) would provide a restraint on further doseindicator display rotation. This feature could take several forms, forexample, missing teeth, filled in teeth, a raised boss or other feature,etc.

The third exemplary embodiment in accordance with the present inventionprovides a simple dose indicator 800 with a ten-dose resolution thatcounts down inhaler actuations from 120 to zero. The exemplaryembodiment provides a dose indicator that can be implemented in adesirably space-efficient manner, allowing for compatibility with pMDIinhalers of familiar shape and size to users, and in particular itsdesign only requires two additional components, thereby meeting themarket need for sufficiently low cost. In addition, this exemplary doseindicator also, advantageously, incorporates a built-in integratedbreath coordination system of the “can't breathe until press” type. Asdescribed above, the labyrinthine follow-through spring 980 comprises aseries of curved spring arms with curved slots 990 between them. Whenthese slots 990 are unobstructed, inhaled air is able to pass throughthem as it makes its way down between the pMDI canister and the actuator100 towards the mouthpiece 120 and the lungs (not shown) of a user.

When the exemplary dose indicator 800 is in its rest position, theseslots 990 are adjacent to the curved bars 930 of the grille element 910provided on the chassis element 810.

In this position, the slots 990 are therefore obstructed, so that whenthe user tries to inhale through the mouthpiece 120, the resulting highresistance to airflow is uncomfortable and prevents significantrespiratory air flow.

As the user presses down on the base of the pMDI canister in order todeliver a dose, as described above, the central alignment tube orindexing element 970 is pushed down by the pMDI valve (not shown). Atfirst, the display element 830 will tend to translate downwards, forexample, from the position shown in FIG. 29 to that shown in FIG. 31. Aswill be noted, this movement causes the curved arms of thefollow-through spring 980 to move away from the slots 920 between thebars 930, 935 of the grille element 910, and the slots 990 in thefollow-through spring 980 to move away from the bars of the grilleelement 910. In this way, an airflow path of low resistance is opened upthrough the two sets of slots 920, 990. Further downward movement of thepMDI valve, and hence of the central alignment tube or indexing element970, will increasingly cause the centre of the follow-through spring 980to move down further than its edges, the latter being impeded byengagement of the lower set of teeth 950 of the display ring 940 withthe lower set of teeth 880 of the chassis element 810 and by theincreasing resistive force from the three counter spring arms 1020 asthey flatten out. As the centre of the follow-through spring 980 movesfurther, to allow actuation of the pMDI valve, the follow-through spring980 will thus tend to adopt a conical shape (not shown).

The third exemplary embodiment described herein provides, amongst otherfeatures and benefits, a self-contained, integrated dose indicator andbreath coordination system for a pMDI inhaler which needs only two extracomponents compared to a standard pMDI inhaler without a dose indicatoror dose counter, and which allows the registering and display of theusage of 120 actuations or more. By using a split-count approach, withpartial indicator advancement on the down-stroke, the count decrementbeing completed on the subsequent up-stroke, advancement of the displayring 940 with respect to the chassis element 810 is ensured.

It will be appreciated that other split-count approaches may also beimplemented which do not require the upper and lower teeth on thedisplay ring 940 and the upper and lower teeth on the chassis element810. For example, indexing features may be provided on the inner wall860 of the chassis element 810 and on the inside of the display ring940, for example, the tab or groove arrangements described in U.S. Pat.No. 5,718,355 particularly at column 15, line 64 to column 17, line 19and in FIGS. 3E to 3H.

Advantageously, all four sets of teeth are provided by only twocomponents which clip together to form a robust module in whichdimensional tolerance issues are substantially reduced. Additionally,the use of the follow-through spring as part of a breath coordinationsystem provides transient flow channel obstruction without incurringcost by having to include additional components.

The dose indicator of the third exemplary embodiment is designed forcount-before-fire reassurance to avoid under-counting of the remainingdoses in the associated pMDI inhaler.

In alternative embodiments (not shown), the curved bars 930 of thegrille element 910 may be configured never to occlude the slots 990 ofthe follow-through spring 980 and/or bypass air channels can be providedbetween the chassis element 810 and the actuator 100, for example, inconjunction with a continuous, non-perforated deformable grille element.Such alternative embodiments serve to provide low cost dose indicationwith minimal changes to the inhaler actuator and a low component count,without breath coordination.

In addition, there is no need for small teeth to be provided on thedisplay ring which is of particular benefit where the display ring is tobe moulded, for example, injection moulded, cheaply from“non-engineering grade” polymer, such as a polyolefin such aspolyethylene or polypropylene.

Although the exemplary embodiments of dose indicators described hereinthat are integrated with breath coordination functionality utilise abreath coordination system of the “can't breathe until press” type,other types of breath coordination system, for example, a transientholding chamber for the fired dose, opened upon subsequent userinhalation, could alternatively be used.

It will be apparent to one skilled in the art that many modificationsand variants can be envisaged, without departing from the scope of thepresent invention. For example, different total numbers of actuationscould be indicated, for example, 100 or 50, rather than 120; and colourbands could be used instead of (or in addition to) numerical indicationson the display ring.

Whilst designed to be compatible with most metering valve types, it willbe appreciated that minor changes to the profiles and forms of thechassis element and the display element may be necessary to incorporatedifferent valve types.

The dose indicator in accordance with the embodiments of the presentinvention can be provided as a sub-assembly for insertion into pMDIinhalers. Alternatively, they could be provided within a separatehousing component, as a stand-alone unit, for example for top-mountingon the base of a container of a pMDI canister as an alternative tomounting within the actuator. However, it will be appreciated that inthis case, modifications within the skilled person's normal technicalskills, for example, modifications linked to mounting the dose indicatoron the base of the container of the pMDI canister, may be needed toensure that the display ring is correctly indexed.

It will be appreciated that, although the dose indicators of the presentinvention have been described for use with an actuator that enables auser to breathe in through his/her mouth, the present invention is alsosuitable for use in nasal actuators where the mouthpiece can be replacedby a nosepiece.

1. A dose indicator for a pressure-actuated metered fluid dispensingdevice, the dose indicator comprising: a chassis element having aviewing portion; a display element located within the chassis element; aresilient deformable element; and an indexing element having an axis,translation of the indexing element along its axis from a first positionto a second position causing deformation of the resilient deformableelement in the same direction as translation of the indexing elementresulting in generally greater displacement of portions of the resilientdeformable element nearer to the axis relative to portions thereoffurther from the axis, the displacement of the portions of the resilientdeformable element in the same direction as translation of the indexingelement inducing indexing of the display element from a current positionto a subsequent position relative to the viewing portion of the chassiselement.
 2. A dose indicator according to claim 1, wherein the resilientdeformable element is arranged around the axis of the indexing element.3. A dose indicator according to claim 1, wherein the outline shape ofthe resulting displacement of the resilient deformable element issymmetrical about the axis.
 4. A dose indicator according to claim 1,wherein the outline shape of the resulting displacement of the resilientdeformable element comprises an inverted frustrum of a cone.
 5. A doseindicator according to claim 1, wherein the display element is arrangedaround the axis of the indexing element.
 6. A dose indicator accordingto claim 1, wherein the display element comprises a continuous displayring.
 7. A dose indicator according to claim 1, wherein the displayelement comprises a discontinuous ring.
 8. A dose indicator according toclaim 1, wherein the display element comprises a disc centred about theaxis of the indexing element.
 9. A dose indicator according to claim 1,wherein the indexing element comprises a tube element connected to theresilient deformable element.
 10. A dose indicator according to claim 1,wherein the resilient deformable element comprises a grille element. 11.A dose indicator according to claim 10, further comprising a furthergrille element located adjacent the resilient deformable grille element,the further grille element substantially abutting the resilientdeformable grille element in the first position to restrict the passageof air through the abutting grille elements.
 12. A dose indicatoraccording to claim 11, wherein, when the indexing element is in thesecond position, the resilient deformable grille element is spaced fromthe further grille element to allow the passage of air through thespaced apart grille elements.
 13. A dose indicator according to claim11, wherein the further grille element is associated with one of: thedisplay element and the chassis element.
 14. A dose indicator accordingto claim 13, wherein the resilient deformable grille element isassociated with the other one of: the display element and the chassiselement.
 15. A dose indicator according to claim 10, wherein the chassiselement comprises a housing including a base portion and a lid portion,the base portion including the indexing element and the resilientdeformable grille element.
 16. A dose indicator according to claim 15,wherein the lid portion is connected to the base portion by a livinghinge.
 17. A dose indicator according to claim 15, wherein the lidportion is closable with respect to the base portion.
 18. A doseindicator according to claim 15, wherein the base portion comprises awall portion having the viewing portion formed therein.
 19. A doseindicator according to claim 15, wherein the housing is formed as onecomponent.
 20. A dose indicator according to claim 15, wherein thedisplay element comprises the further grille element and is housedwithin the housing.
 21. A dose indicator according to claim 20, whereinthe further grille element is substantially rigid.
 22. A dose indicatoraccording to claim 20, wherein the further grille element is fixed. 23.A dose indicator according to claim 20, wherein the display elementfurther comprises a rack formed on a portion thereof by which it isindexed with respect to the viewing portion.
 24. A dose indicatoraccording to claim 23, wherein the display element is formed as onecomponent.
 25. A dose indicator according to claim 23 or 21, wherein thehousing further comprises a worm element arranged to engage with therack formed on the display element, rotation of the worm elementindexing the display element with respect to the viewing portion.
 26. Adose indicator according to claim 25, wherein the worm element comprisesa plurality of teeth located on at least a portion thereof.
 27. A doseindicator according to claim 26, wherein the worm element comprises anaxle portion at each end, the plurality of teeth being located betweenthe two axle portions.
 28. A dose indicator according to claim 26,wherein the housing further comprises a locking pawl for engaging withat least one tooth formed on the worm element.
 29. A dose indicatoraccording to claim 25, wherein the worm element is supported by firstand second support members formed on the chassis element.
 30. A doseindicator according to claim 29, wherein the first and second supportmembers are integrally formed with the lid portion.
 31. A dose indicatoraccording to claim 29, wherein the first and second support members eachhave a through-hole to receive an end of the worm element, thethrough-holes being capable of being moulded using an injection mouldingtool that opens along an axis substantially perpendicular to an axisdefined by the centres of the through-holes.
 32. A dose indicatoraccording to claim 25, wherein the base portion includes an advancementarm which is operable to rotate the worm element as the indexing elementmoves between the first and second positions.
 33. A dose indicatoraccording to claim 32, wherein the advancement arm and base portion areintegrally formed.
 34. A dose indicator according to claim 25, whereinthe spacing of the rack corresponds to the flight of the worm element.35. A dose indicator according to claim 15, wherein the lid portioncomprises at least one additional spring arm that engages an associatedhole provided in the side of the indexing element.
 36. A dose indicatoraccording to claim 10, wherein the chassis element comprises an innerwall portion and an outer wall portion joined by a rim portion, theinner and outer wall portions defining an annulus therebetween, thedisplay element being mounted within the annulus with a portion thereofbeing visible through the viewing portion formed in the outer wallportion.
 37. A dose indicator according to claim 36, wherein the chassiselement includes a first set of chassis element teeth located within theannulus adjacent the rim portion and a second set of chassis elementteeth associated with the outer wall portion and spaced from the rimportion.
 38. A dose indicator according to claim 37, wherein the outerwall portion comprises a plurality of clip elements extending therefromon which the second set of chassis element teeth is formed.
 39. A doseindicator according to claim 37, wherein the first and second sets ofchassis teeth face one another and are integrally formed with thechassis element.
 40. A dose indicator according to claim 37, wherein thefirst and second sets of chassis element teeth are offset with respectto one another.
 41. A dose indicator according to claim 37, wherein thechassis element is formed as one component.
 42. A dose indicatoraccording to claim 37, wherein the display element comprises first andsecond sets of display element teeth located on respective peripheraledges thereof, the first and second sets of chassis element teethengaging with respective ones of the first and second sets of displayelement teeth in accordance with the first and second positions of theindexing element.
 43. A dose indicator according to claim 42, whereinthe display element comprises the resilient deformable grille elementand the indexing element, the resilient deformable grille elementconnecting the display element to the indexing element.
 44. A doseindicator according to claim 42, wherein the display element is formedas one component.
 45. A dose indicator according to according to claim42, wherein the translation of the indexing element to the secondposition causes engagement of the second set of chassis element teethwith the second set of display element teeth to rotate the displayelement through a fraction of an indexing pitch in a first direction,and translation of the indexing element back to the first positioncauses engagement of the first set of chassis element teeth with thefirst set of display element teeth to rotate the display element througha remaining fraction of the indexing pitch in the first direction.
 46. Adose indicator according to claim 45, wherein the chassis elementfurther comprises a chassis element spring arranged to maintainengagement of the first set of chassis element teeth with the first setof display element teeth when the indexing element is in the firstposition.
 47. A dose indicator according to claim 46, wherein thechassis element spring comprises the further grille element, the chassiselement spring being connected to the inner wall portion.
 48. Apressure-actuated metered dispensing device comprising: an actuatorportion; a window formed in the actuator portion; a dispensing portion;a nozzle block located between the actuator portion and the dispensingportion; a dose indicator according to any one of the preceding claims,the indexing element being aligned with the nozzle block and the viewingportion being aligned with the window in the actuator portion; and acanister comprising a container and a metering valve housed within theactuator portion, the metering valve having a valve stem that engagesthe nozzle block and wherein, in use, relative movement of the containerand the nozzle block causes the translation of the indexing element fromthe first to the second position as a result of engagement of a portionof the canister and the indexing element.